Wednesday, June 14, 2006

Darwiniana: evolution and string theory

I always like to say that the status of string theory and the status of the theory of evolution - and the characters of their critics - are somewhat analogous: I summarize the reasons at the end of this text.

Many people remember - and some of them have participated in - a funny story in which a group of believers felt that this opinion of mine insulted their religious sensibilities. Clifford Johnson refused to help them, so they virtually marched to Jacques Distler's office and forced him to make a statement on behalf of the whole string community and officially denounce my analogy, much like the believers who demanded the denunciation and execution of the heliocentric heretics 500 years ago. ;-) Please, Prof. Distler, we want our belief to be restored and we want to be able to sleep at night and raise our children. As you can expect, Jacques Distler has fully obeyed their requests.

This almost sounds like a story from the New Testament except that in the past, there would be 1 Judas in such a story. Today we have 387 Judases with various confused and triply corrupt self-interests and relations to the bad players in the game of life.

a blog attempting to be a place for politically balanced (...) debates about the origin of life, if I understand it well (it links both to Pharyngula as well as Uncommon Descent), agrees with my analogy and thinks that it is unfair that string theory is subjected to the acid test while evolution is given a free ride:

... But physics is hardly finished yet. Horgan’s remarks, put somewhat differently, with the ‘end of science’ idea sidelined, would apply better to evolutionary theory which trespasses various demarcation problems and creates a set of theories that are certainly not experimental, and certainly not properly empirical, so far. ... The public is being misled here: String theory is subjected to the acid test, but Darwinism always gets a free ride, often from the same theorists. The public is being kept bewildered by this contradiction, which borders on fraud.

It should not be hard for me to find things on that blog that I would disagree with - because I am a Darwinist after all - but because the point above is right on the money, I reposted it.

Why are evolution and string theory analogous

(taken from the fast comments under the article about the Dean of crackpots and Hitler's Pope)

The reason why the situations of string theory and evolution are analogous is that both of them are more or less inevitable given the known data, known approximate laws of Nature, and known and derivable logical constraints.

No minor, small observations would be enough to rule out the whole framework of evolution or the whole framework of string theory because we have much stronger reasons to be nearly certain that the general pictures are correct and our job is to complete the details. Surely, we don't abandon evolution after the first surprising observation of the genes of XY where XY does not stand for Xi Yin. In the same way, we don't abandon string theory once we find out that the simplest compactification - on torus - is not realistic.

Evolution is the only known way - and probably the only possible way - how to logically reconcile the rich spectrum of complicated life forms, their shared molecular and other features, their diversity, currently observable mechanisms that decide about the survival, and the history of the Earth and the Universe including the obvious life-less beginning.

String theory is the only known consistent way - and probably the only possible consistent way - how to logically reconcile the known rich spectrum of particles and forces, including gravity, in a quantum setup, how to properly reflect their known interactions, and the known behavior of particle physics and general relativity at different energy scales. It is the only way to go beyond quantum field theory without sacrificing its proven features, and because we almost certainly know that we must go beyond ordinary local field theory, string theory seems to be the only game in town, despite three unsuccessful decades of attempts to show that there could exist alternatives.

In the case of evolution, the evidence is more of an observational character and the basic logic is comprehensible to many people; in the case of string theory, the evidence is much more strongly based on mathematical reasoning that is comprehensible to a limited set of experts.

The life forms that existed four billion years ago cannot be directly observed; physics at the Planckian or GUT scale energies cannot be directly observed either. In both cases, we can obtain indirect information that is encouraging and consistent with the picture that was derived from a different starting point.

In both cases, it is hypothetically plausible that there exists another theory and the only reason why we can't find it is our lack of imagination. In both cases, such a possibility is equally unlikely. In the context of evolution, it is because the arguments showing that the rough picture has to be correct are apparently pretty simple to follow and check. In string theory, it is because we have seen many checks that all newly emerging good ideas that looked like alternatives were actually shown to be a part of string theory, and this repeated experience is a nontrivial confirmation of the uniqueness of the structure.

Both string theory and evolution have critics who claim that string theory and evolution are not falsifiable. In both cases, the theories are viewed as "not falsifiable" because at least to some extent, the inevitability of the frameworks has already been proved which makes it hard to falsify it.

A difference: the basic framework of evolution is believed to be completely known. The most universal conceivable definition of string theory is believed to be unknown. In this sense, evolution is more dogmatic while string theory is more open-minded work in progress.

We have said that falsifiability is criticized by critics of both frameworks. However, in both cases, striking (but unlikely) ways to falsify them in principle exist - for example some brutal violations of the equivalence principle without new forces and hundreds of other sick physical effects predicted by the "alternatives" but prohibited in string theory. Evolution can be falsified by God who appears in front of our eyes and tells us how He did it, by observation of traces of species identical to the present ones that lived 5 billion years ago, and other possibilities.

In both cases, the attack is led by people with poor quantitative skills who dislike a careful and detailed technical analysis of the scientific issues and prefer sociological arguments, conspiratory theories about hypothetical mafias, methods to gain political power, and ways to convince many people about their "simple solutions" using the paradigms of the "asymmetric warfare". This description is primarily about William Dembski and Peter Woit but its validity is probably more general.

In both cases, the known "alternatives" are completely ridiculous and absurd, logically inconsistent, usually millions of times excluded by observations, and having no predictive power. No inner mechanism of Intelligent Design can be found, much like in loop quantum gravity that has infinitely many undetermined parameters - and even this infinite-dimensional family of theories is clearly not enough to include theories that at least remotely agree with rough qualitative features of the world around us.

The alternatives are only proposed as a "proof of concept" - namely that one can say a couple of silly sentences and find political tools to argue that these sentences are serious alternatives, despite all of the proofs that they can't work in any scientific sense.